1. Field of the Invention
The present invention relates to a heating roller device for use in a device for heating and fixing toner in a copying machine, a laser beam printer or the like, a device for laminating steel plates, a device for laminating plastic films or the like.
2. Description of the Related Art
A major portion of fixing portions of copying machines, such as the copying devices and laser beam printers, has a structure formed as shown in FIG. 16. Toner powder 2 is transferred to a sheet 1 made of paper or the like by dint of static electricity, and then the sheet 1 is allowed to pass through a position between a heating roller 3 and a pressing roller 4. As a result, toner powder transferred to the surface of the sheet 1 is heated, melted and pressed so as to be fixed to the surface of the sheet 1. The heating roller 3 has a heat source which is a halogen lamp heater 5 disposed in the central portion of the heating roller 3. A thermistor sensor 6 disposed to be in contact with the surface of the heating roller 3 detects the temperature of the surface of the heating roller 3. Thus, the output from the halogen lamp heater 5 is controlled in such a manner that the foregoing temperature is made to be a predetermined temperature level.
Hitherto, a method capable of joining the temperature sensitive metal and the aluminum plate to each other and arranged as shown in FIG. 17 has been suggested. That is, two plate-like members 23 and 24 are heated to about 400.degree. C. in a heating furnace 25, and then allowed to pass through a position between rollers 26 to which a pressure is applied so as to be jointed to each other.
The heating roller devices typified by the above-mentioned copying device have a problem in that the temperature of the heating roller cannot easily be controlled. That is, the convenience of users has been satisfied by making the copying device to be adaptable to various sizes. The heating roller is arranged to be adaptable to, for example, A3-size so as to be capable of copying original documents having A5 to A3 sizes. If paper having the A5-size is copied, a structure, in which the temperature of a portion through which paper is allowed to pass is made to be constant, causes heat of the portions, through which paper is not allowed to pass, not to be deprived by paper. As a result, the temperature of the heating roller is raised excessively. Therefore, the temperatures of the heating roller can be uniformed only when a plurality of temperature sensors are attached and the heater serving as the heat source is sectioned so as to be individually controlled. If a unit for controlling the temperature suffers a breakdown, the temperature of the heating roller is raised excessively. Thus, there arise problems in that paper is burnt and a resin film is melted in a case where copying to the resin film is performed.
Moreover, a conventional method of joining the temperature-sensitive magnetic metal and the aluminum plate to each other suffers from a problem in that any pipe cannot be manufactured although a flat plate can be manufactured by joining. That is, if ends of the temperature-sensitive magnetic metal having a melting point of about 1200.degree. C. are welded so as to be formed into a pipe, aluminum adjacent to the foregoing metal is undesirably melted. Aluminum has a melting point of about 600.degree. C.